Coke oven ascension pipe offtake means



L.. ALDERMAN 3,309,286

March 14, 1967 I COKE OVEN ASCENSION PIPE OFFTAKE MEANS Filed Aug. 2, 1965 2 Sheets-Shea?I l March 14, i967 L, ALDERMAN v 3,309,286

COKE OVEN ASCENSION PIPE OFFTAKE MEANS Filed Aug. 2, 1965 2 sheets-sheet 2 x l l f l l 1 1 United States Patent O This application is a continuationin-part of our copending application Ser. No. 270,735, led Apr. 4, 1963, now abandoned.

This invention relates to improvements in coke oven ascension pipe offtake means and in particular to the -arrangement of the liquor sprays therein.

The prime purpose of these sprays is to cool the gases issuing from the coking chambers of the ovens before they are passed to the collector mains. The present invention is, however, concerned with a secondary cleaning action of these sprays.

Ascension pipes in coke ovens are installed, one (or two) at each oven of a coke oven battery, to draw off the coal gas formed in the oven during carbonisation of the coal charge; the gas being transferred through a 'conduit bend in each ascension pipe into a collector main or mains running along one or both sides of the battery. The gas may subsequently be used for heating the ovens for the carbonisation of the coal charges therein.

The gas produced by car-bonisation enters the ascension pipe at a high temperature, and to protect the ascension pipes against the extreme heat -they are lined With refractory material.

To cool the gases, it is normal practice to fit a liquor spray in the outer wall of an unlined conduit bend connecting an outlet from the ascension pipe to a collector main, and to spray liquor continuously into the gas stream. This cooling causes deposition of heavy tar condensates which cling to the walls of the bend and after building up in thickness reduce its effective bore.

ln the subsequent stages of carbonisation the gases are evolved at higher temperatures, resulting in the distillation of the heavy tar condensate deposits, leaving a hard carbonised residue which is difficult to remove. It thus becomes necessary to remove these deposits periodically by manual or mechanical means. This is an yunpleasant and difficult task and is only partly effective, as it is almost impossible to remove the deposit from the inner wall of the outer periphery of the bend.

It has been observed -that these deposits do not occur to any noticeable extent upon those parts of the bends which are under the direct influence of the sprays, but only upon those portions which, due to the form and position of the sprays, are incompletely sprayed, or not sprayed at all. Previous forms of ascension pipe top assemblies have not, however, made full use of this cleaning action of the sprays since it involves risk of spalling damage to the refractory lining if the spray liquor is brought too close to the lining and comes into contact with it.

The object of the present invention is to utilise the secondary cleaning action of the liquor spray to produce an ascension pipe oiftake means which is self-cleaning and does not require the regular cleaning maintenance referred to, and which involves no contact of sprayed liquor with the ascension pipe lining.

To achieve this object it has been necessary to precisely position the spray nozzle within the conduit bend, to accurately dene the boundary of the spray cone produced by the nozzle with respect to the refractory lining of the ascension pipe and then to ensure that no sprayed liquor can run back on to this refractory lining, which would result in spalling of the refractory.

ICC

According to the invention therefore, there is provided coke oven ascension pipe off-take means comprising:

(a) An ascension pipe,

(b) An outlet from said ascension pipe,

(c) Refractory lining to said ascension pipe and to said outlet of heat conductivity sufficiently low to prevent deposition of tar upon said lining,

(d) An unlined conduit bend attached to said ascension pipe outlet,

(e) Liquor spray nozzle means located within said conduit bend closely adjacent the junction thereof with the ascension pipe outlet for producing a spray cone a portion of whose boundary lies closely adjacent the interface of the outlet and the conduit bend, said spray cone lying Wholly within the conduit bend and wetting all the inner surface thereof exposed to the flow stream of gas within the bend, the nozzle means being recessed to lie outside said llo-W stream, and

(f) Means for preventing the access of sprayed liquor` to said refractory lining from said conduit bend. l

A better understanding of the invention may be obtained from the following description when -this is read with reference to the accompanying drawings. This description is given by way of example of the invention only Iand not by Way of limitation thereof.

In the accompanying drawings:

FIGURE 1 is a vertical section through the upper portion of a coke oven ascension pipe, portion of a gas collector main and the connection therebetween;

FIGURE 2 is a section on the line 2-2 of FIGURE 1; and

FIGURE 3 is a view, similar 4to FIGURE 1, of a further form of the invention.

Referring to the embodiment of FIGURES 1 and 2, the ascension pipe 11 is of known type and comprises a vertical pipe 12 lined With refractory material 13 and open at its lower end to the lcoking chamber of a coke oven in known manner. At its upper end, the pipe 12 is open t0 a refractory-lined T-piece 14, the outlet 15 of which is directed away from the oven structure (not shown). The upper opening 16 of the T-piece 14 is closed by a suitable pivoted cap 17. The refractory lining 18 of the T -piece 14 ceases at the outer end of the outlet 15 in abutment with a thin metal disc 19 which has a central aperture 20 of the same diameter as the central passage through the refractory lining 18 in the outlet 15.

The reason for continuing the refractory lining 18 of the ascension pipe into the T-piece outlet 15 is to ensure that, in operation, condensation of heavy tar products in the gas does not commence until the gas leaves the T- piece.

The refractory lining of the ascension pipe and of the T-piece are formed of refractory brick, Iand the heat conductivity of the lining has a value sufficiently low to prevent deposition of tar on the lining due to drop in temperature of the gas in its passage through the ascension pipe.

To the outer surface of the metal plate 19 is abutted one end of a conduit bend 21 through which gas passes via an isolating valve 30 to a collector main 28. The conduit bend 21 is secured, in abutment with the metal plate 19, to the open end of the T-piece outlet 15. The inner diameter of the bend 21 is greater than the inner diameter of the refractory lining 18 at the outlet, and the metal plate 19 and adjacent end of the bend 21 thus define an annular step 22 having the s-ame depth as the refractory lining 18. v

At the upper end of the bend 2.1, closely adjacent its point of attachment to the outlet 15, a spray nozzle 31 is inserted through the wall of the bend so that it lies at an angle from the vertical inclined towards the ascension pipe 11. This nozzle 31 is connected to the liquor spr-ay system of the oven by a conduit 32.

The nozzle 31 projects only so far into the bend 21 that it is wholly contained in the annular step 22 at the junction of the bend 21 and the T-piece outlet 15, and does not project into the gas stream flowing in the bend 21. By this means, condensation of tar on the spray nozzle is avoided. The spray hole or holes in the nozzle 31 are so arr-anged that an upper portion 33 of the boundary of the spray cone produced by the nozzle is substantially horizontal and directed away from the metal plate 19, whilst a lower portion 34 of the spray cone boundary is vertical, and lies closely adjacent the interface between the outlet and the conduit bend 21. Thus the spray cone is located wholly within the bend 21. No spray liquor is allowed to fall on the refractory lining 18, but the whole of the interior of the bend 21 is continually and completely wetted. The presence of the step 22 between the conduit bend 21 and the outlet 15 prevents sprayed liquor from running into the outlet 15.

In the operation of the assembly, hot coke oven gas formed in the coking chambers of the oven passes up the ascension pipe 12 to the outlet 15, its temperature being maintained as hereinafter discussed by the insulating function of the refractory lining 13. Upon emerging from the outlet 1S to the unlined conduit bend 21 it immediately meets the spray liquor boundary 34 and is cooled, causing condensation of tar. Part of this condensed tar is carried in the gas stre-am past the isolating valve 30'to the collector main 28. The remainder is precipitated on to the walls of the conduit bend 21, but since the whole of the bend exposed to the gas stream is either directly sprayed with or wetted by liquor from the nozzle 31, it is continuously washed from the walls of the conduit bend into the collector main. Thus no build-up of deposit occurs on the walls of the conduit bend to be carbonised at a later stage of the `coking cycle. The offtake means is therefore self-cleaning in its action, and no routine cleaning maintenance is required as in known ascension pipe otftake layouts.

In the form of the invention shown in FIGURE 3, the refractory lining of the ascension pipe and its outlet is a composite layer comprising a layer of insulating refractory brick 40 adjacent the wall 12 of the ascension pipe and the wall 15 of the outlet, and a further layer of fireclay refractory brick 42 upon the layer of insulating brick 40. The reclay brick 42 is thus exposed to the flow of hot gas within the ascension pipe and outlet, while the insulating brick 40, which is protected from the hot gas stream, serves to lower the overall heat loss through the refractory lining due to its relatively low coecient of heat conductivity.

In any individual installation, the choice of a single or composite refractory lining depends on factors such as the gas velocity within the ascension pipe, the volatile matter content of the coal being carbonised, and the temperature in the free space at the head of each oven chamber during operation. In either case, it is essential for the purposes of the invention that the overall heat conductivity of the refractory lining is suiiciently low to prevent deposition of tar upon the lining due to cooling of the gas in its passage through the ascension pipe. In some cases, a drop of or 30 C. may be large enough to cause such deposition.

In the embodiment of FIGURE 3 the means employed I to prevent sprayed liquor from running back from the conduit bend 15 on to the refractory lining 42 is as follows. In place of the step 22 of FIGURE 1, a portiony 44 of the conduit bend opposite to the spray nozzle 31 is angled downwardly from the junction of the bend 21 and outlet 15. The inner surface of the bend portion 44 is thus disposed at an angle to the general direction of irnpingement of the spray, and so directs the spray away from the ascension pipe outlet and prevents sprayed liquor from running on to the refractory lining 42. A small step 46 is formed in the portion 44 of the conduit bend, and the spray cone from the nozzle 31 is precisely aligned so that the portion 34 of the spray cone boundary falls just within the step 46.

For the object of the invention to be achieved in respect of the self-cleaning action of the spray, precise alignment of the nozzle 31 is necessary to ensure correct location of the spray cone within the bend 21, and correct location of the boundary portion 34 with regard to the termination of the refractory lining 42, as hereinabove described.

It is also necessary for the angle subtended by the spray cone at the nozzle 31 to be precisely defined. The nozzle 31 is located just outside the flow stream of the gas issuing from the outlet 15. In FIGURE 3 the approximate upper boundary of this flow stream is shown at 4S, meeting the upper wall of the conduit bend at 50, and the approximate lower boundary of the flow stream is shown at 49, meeting the lower wall of the conduit bend at 51. It is at positions downstream of the points 50 and 51 that deposits are liable to build up on the surface of the bend. The angle subtended by the spray cone at the nozzle is therefore arranged to be such that spray impinges on the bend upstream of the points 50 and 51. Not only is the nozzle 31 protected from the formation of deposits by lying outside the fiow stream of the gas, but so also are those portions of the inner surface of the conduit bend adjacent the nozzle and up to the point 50.

The only other part of the bend 21 which is not in the direct path of spray from the nozzle is the inner lower portion 52. This is, however, effectively wetted by sprayed liquor running downwards oif the angled portion 44.

I claim:

In combination with a coke oven ascension take oif pipe, means defining a lateral gas outlet in said pipe, and a `refractory lining at the inner surface of said pipe and said outlet and having suiciently low heat conductive properties that heat loss through said lining, pipe, and outlet is low enough to prevent deposition of tar upon the internal surface of said lining, an unlined conduit bend adapted to connect said pipe to a collector means and having angularly related inlet and outlet openings, said conduit bend being connected to said pipe with its outlet opening facing downwardly and with its inlet openlng in aligned, direct communication with said gas outlet to provide a continuation of the gas flow passage defined by said gas outlet, means providing an annular, radially extending step at the interface between said gas outlet `and said inlet opening, surface means formed in sald conduit bend and cooperating with said annular step to provide an abrupt radial enlargement of said gas flow passage, said enlargement being in the direction of gas flow through said g-as outlet and said conduit bend to provide for the initial peripheral impingement of the main gas stream flowing through said conduit bend at a reglon on the conduit bend internal wall surfaces that is spaced a predetermined distance downstream of said inlet opening, said surface means, said annular step, and the periphery of said gas stream before it impinges on said internal wall surfaces delimiting an annular pocket, 11quor spray nozzle means disposed entirely within said pocket immediately adjacent to said annular step for providing a liquor spray cone (a) which peripherally impmges on the internal wall surfaces of said conduit bend at a region upstream from the region where said gas stream initially impinges on said internal wall surfaces and (b) which wets all of the interior conduit bend wall surface extending downstream from its region of initial impingement, and further surface means cooperating with said annular step for directing the sprayed liquor away from said gas outlet to prevent access of said sprayed liquor to said refractory lining.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS Plantnga 202-258 Cole 202-254 5 Potter 1202-258 Koppers 202-254 6 2,759,885 8/1956 Thompson 202-256 FOREIGN PATENTS 744,440 l/ 1944 Germany.

MORRIS O. WOLK, Primary Examiner. JOSEPH SCOVRONEK, Examiner. 

